The important thing for me about an online store is the search function and I find the new sites search engine to be far superior!
As a test I typed in "Hornby class 50" into the current site and it gave me 6 pages with 446 results, the whole of the first page (72 results) were steam locos, then on page 2 another 47 steam locos before finally getting to the diesel class 50's, nothing on page 3, one on page 4, a few on page 5 (finally including the two newest just released models) and nothing on page 6...
Compare that to the new sites search for the same "Hornby class 50" and it's narrowed down to just 22 results on 1 page, and the first 12 results were Hornby class 50's! No more scrolling through pages of stuff I don't want to look at!
So there are some positives. The search is much tighter.
Due to numerous problems with orders from Hattons I stopped using them this year and cancelled all my pre-orders for everything and transferred them to other retailers except for stuff I can't get elsewhere like Hattons exclusives, but I will say that the search functions on the new site impresses me.